NOTE: The relative proportion of exports to total merchandise trade varies in current and real terms because of variations in the price indexes used in adjusting exports and imports for inflation. NA = Not applicable.

SOURCES: U.S. Department of Transportation, Research and Innovative Technology Administration, Bureau of Transportation Statistics, based on data from: Current-U.S. Department of Commerce, Bureau of Economic Analysis, U.S. International Transactions Accounts Data, available at www.bea.gov/international/bp_web/list.cfm?anon=106637 as of Sept. 24, 2009. Real-U.S. Department of Commerce, Bureau of Economic Analysis, National Income and Product Accounts, available at www.bea.gov/national/nipaweb as of May 20, 2009.